Trichoderma spp.

Trichoderma is a saprophyte fungus, which belongs to the family Hypocreaceae, the division Ascomycota. Different varieties of this fungus are used in agriculture against various phytopathogenes of crops in outdoor planting and glass-covered ground. Such species as T. harzianum, T. hamatum, T. lignorum and their biotypes have the most biological and commercial importance.

The active components of biopesticides made on the base of this fungus-antagonist are their spores, mycelium and products of metabolism. In the process of development Trichoderma synthesizes a lot of antibiotics (gliotoxin, viridine, trichodermin and others). They destroy the cell walls of phytopathogene fungi and produce biologically active substances, which stimulate plant growth and development. Trichoderma is able to suppress more than 60 species of pathogens (Pythium, Botritis, Phoma, Sclerotinia, Fusarium, Ascochyta, Alternaria and others) on different plants (cucumbers, tomatoes, cabbages, peppers, various ornamentals, cereals and grain legume crops).

Nowadays they are known two mechanisms of genus Trichoderma biological control: a rhyzosphere competence and an induced system resistance. Both of them provide longtime plant defense.

The microorganism colonization of plant roots increases yield-capacity. After the treatment of seeds with the conidia of Trichoderma or their penetration directly in soil the introduced conidia colonize root surface. It increases absorbing surface making biological obstacle against the pathogens. The full root colonization with Trichoderma occurs at the time of seed treatment when the granular form of the fungus is incorporated on the surface of plowed soil and under tillage or ripping. In a greenhouse the colonization is realized by way of the addition of biofungicide in soil mixtures. The rhizospheral colonization by the fungi of Trichoderma geneses causes the suppression of plant diseases, the speeding-up of growth processes, the increase of the resistance to diseases and unfavorable weather conditions (for example draught). Trichoderma biofungicides are able to suppress not only the agents of seed, root end soil infections but the disease development of fruits and vegetative mass by way of the laying of these substances on their surfaces. These biofungicides can be effective against the powdery mildew, the grey and the white rot, the mildew and other diseases. It is necessary to incorporate the conidia of Trichoderma every 10–15 days for the control of the mentioned phytopathogenes.

There are some limitations for the application of Trichoderma biofungicides. At first they are preventive only because biofungicides are usually not able to control the diseases, which have already developed. Scientific researches have shown that the development of Trichoderma isolates is suppressed by the high density of phytopathogene population. Trichoderma biofungicides are recommended to apply as a component of the integrated system of plant defense.

The fungicides containing Trichoderma are effective at temperatures more than 14°C (the optimal threshold of development is observed at 24–28°C). The using of the conidium forms of the fungicides makes their application independent on the conditions of relative air humidity.

The fungus Trichoderma is harmless for homeothermal (hot-blooded) animals, beneficial entomofauna and bees. Its fungicides don't cause the heat injuries of plants.